function saveJSON(data, filename){
    if(!data) {
        alert('保存的数据为空');
        return;
    }
    if(!filename) 
        filename = 'json.json'
    if(typeof data === 'object'){
        data = JSON.stringify(data, undefined, 4)
    }
    var blob = new Blob([data], {type: 'text/json'}),
    e = document.createEvent('MouseEvents'),
    a = document.createElement('a')
    a.download = filename
    a.href = window.URL.createObjectURL(blob)
    a.dataset.downloadurl = ['text/json', a.download, a.href].join(':')
    e.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null)
    a.dispatchEvent(e)
}